Research involving children with cancer experiencing pain is centered in three areas: clinical evaluation, descriptive studies, and therapy. For clinical evaluation, 3 different modalities of pain measurement viz. a visual analog scale, a verbal descriptor scale, and a picture scale are being compared to evaluate their feasibility of administration and reliability in children of all ages experiencing acute or chronic pain. Descriptive studies consist of (1) The prospective study of the predictive factors and nature of phantom limb pain and sensations in patients undergoing amputation and (2) The study of the prevalence and nature of pain in a childhood cancer population at initial presentation. Therapeutic studies in progress are: (1) Study of the efficacy and kinetics of a continuous intravenous or subcutaneous infusion of morphine sulfate in patients with malignancy who are experiencing pain, in which the pharmacokinetics of morphine and changes in blood Beta endorphin level are being studied in children requiring widely differing morphine doses to control severe pain; morphine kinetic data is also being obtained in a primate model, (2) Study of the use of nitrous oxide for children with malignancy undergoing painful procedures.